Topic outline

  • Light and Its Partners

    The goal of all that projection equipment and screen and comfy seats is to get the Artist's Intent from one person to many. 

    Simple concept, yes, but it requires the talent of many professions and people, the combined ingredients of many nuanced technologies, hundreds of pieces of equipment (many under constant development), and many steps and mediums and modes of transport. Even though our focus is on Movies in Cinemas, the same applies for presentations on TV and computers.

    For the image, the most essential ingredient is light. Lenses capture light bouncing from scenes and talent, sensors capture some of that light, editors manipulate that light, and colorists manipulate it again to make it right for each receiving device that follows. At each stage the light is stored and transported as film (more and more rarely) – or digits (more and more often) on drives – until finally it is prepared for a movie projector's 3 sensors that reflect the light through the final lens to the screen – and then to an audience.

    Getting a piece of work from the mental world of the author's and director's intent to the mental world of watching with a "willing suspension of disbelief1" has long been a process of literature and theater. For the last 100 years in most of our cultures, it has been the process of movies.

    Light is the predominant feature, so, that is where our adventure in learning begins. Our goal is a usable understanding. 

    And for a view of where we end, here is a snip of SMPTE 431-1:

    "D-Cinema Exhibition Screen Luminance Level, Chromaticity, and Uniformity,” is a standard that specifies the reference values and tolerances for the screen luminance level, white point chromaticity, and luminance and chromaticity uniformity of the projected light for the presentation of digital motion pictures in review rooms and commercial cinemas. Because the perception of color and contrast is dependent on the absolute luminance of an image, the goal of 431-1 is to achieve the look in the projected image that will correspond to the look produced during the mastering process.

    We'll cover what this means, and more. We'll quickly find out that light exists, but in the process things get a bit confusing, partly because what we see as colors doesn't really exist. 

    1 – Samuel Taylor Coleridge – 1817 – Biographia literaria

  • The Eye

    The eye is the major physical component that determines the effect which light has upon us.

    Obviously, the eye can be studied for years. Not so obviously, there are processes that are still only guessed at. Being responsible for the light that bounces from the screen and into the eyes of your patrons, you need to know a little bit about the eye.

    We are not going to make this a year long study. But we need to know enough that we are not tricked as we go through the steps of providing the best audience experience. These first parts will be added to as we discover more about the components of light further on.

  • Electromagnetic Spectrum

    If we were to count waves while on the beach, we might say there were a hundred in the 10 minutes of our visit. But if we wanted to use the most common measurement unit, we would mention the frequency in terms of 'cycles per second'. If one wave comes along every 10 seconds, we could say that the frequency of the waves are .1 cycles per second. Likewise, a wave every 8 seconds would be .125 cycles per second.

    A piano is tuned so that the note "A" below middle "C" is 440 cycles per second (cps). One octave below that is 220 cps, and the octave below that is 110, and so on.

    Though easy to understand, even this is not up to the standards of today. In 1960 the International System of Units (which takes the abbreviation SI from the official French language of the standards bodies who determine these things) replaced the common term cycles per second with the term hertz. It is named after the German physicist Heinrich Hertz who, before he died at age 36 in 1894, helped clarify the components of light and expanded our knowledge of the electromagnetic theory of light.

    If we believe most early texts, before light there was chaos. Before Hertz, there was indeed chaos in the study of light.

    • The XYZ Colorspace

      It is impossible with technology, yet we see it everyday.

      And to get started we'll explain why it is all theory. There is good science to show that there are 4 stimulus capabilities in the human eye, but that one gets filtered. Certain other animals do, why shouldn't we?

      Tri-stimulus or not, we're here to say that color doesn't exist – and soon you'll say it too.

      • Understanding XYZ Page
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    • Temperature and White Point

      One has to constantly speak of Planck. We think of Einstein when we think of quantum physics, but it was Planck who was able to describe the confusions of it five years before the famous patent clerk in Switzerland wrote his famous papers about it.

      This study describes that line in the color spaces that describes the white point taken from a radiating black body.

      • White Off The Line Page
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    • Luminance and Chromaticity

      Could grey really be white with less luminance?

      Can we use the word 'Steradian' without breaking the promise of not using math?

      • Luminance and Chromaticity Page
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    • Foot Lamberts, nits (pi candellas per meter)

      “The nice thing about standards is that there are so many of them to choose from .”
      The great naysayer, Professor Andrew S. Tanebaum

      We have worked so hard at avoiding mathematics, so we'll honer Mrs. Lambert's son, a great mathematician in optics (among other things), then say good-bye to him.

      • Foot Lamberts, nits (pi candellas per meter) Page
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    • Grey Scale Tracking

      Not all illusions use grey, but enough simple and great ones do that we will use this topic to show how difficult it is to trust your eyes.

      This story begins with an odd definition: IRE. What does the Institute of Radio Engineers have to do with how your picture looks? It is not a gray area. Well actually, it is a gray area.

      • Grey Scale Tracking Page
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